New techniques to grow sperm from immature sperm stem cells may provide a way to restore fertility in prepubescent boys treated for childhood cancer. Credit: Getty Royalty Free

Researchers have found a way to make sperm from sperm stem cells in mice, giving hope that young boys treated for childhood cancer who are frequently left infertile, may be able to have children as adults.

Previously, only males who had reached puberty by the time of treatment were able to donate sperm for freezing and future use, but the new research suggests that preservation of fertility for even young boys may be possible.

"We have never had any fertility preservation options for prepubescent boys. The findings in this work are a great first step forward for our youngest patients," said study co-author Jill Ginsberg, MD, a pediatric oncologist and director of the Cancer Survivorship Program at Children's Hospital of Philadelphia.

One in 530 young adults in the U.S. is a survivor of childhood cancer and survivors can experience a variety of long-term effects. Fertility issues are reasonably common and three-times more male survivors experience them than female survivors. Both certain chemotherapies and radiation therapy can kill the cells that produce sperm and render males infertile.

Previous research has shown that it was possible to perform a transplant of sperm stem cells from donors into the testes of infertile mice, restoring their fertility. However, the testes of prepubescent boys contain so few immature sperm cells that it would be impossible to do this without multiplying them in the lab.

The work published today in Nature Communications explains how they achieved this by isolating particular cells from the testes called endothelial cells, which they found to be critical in supporting the growth of the immature sperm cells. They also identified a cocktail of 5 key proteins produced by these endothelial cells that were essential to keep the sperm stem cells alive and replicating, long-term. They then tested their method in infertile mice and were able to restore fertility, proven by the male mice fathering pups.

"For years researchers have been trying to find ways to grow and expand these cells from testicular biopsies donated by young patients prior to their cancer treatment, but until now, there has not been a consistently successful approach," said Sandra Ryeom, PhD, leader of the work and an associate professor of Cancer Biology in the Perelman School of Medicine at the University of Pennsylvania.

This initial research was done in mice and has yet to be proven in humans, but the researchers hope they will be able to take small samples of these immature sperm cells from prepubescent boys undergoing cancer therapy, bulk them up in the lab and then freeze them for survivors.

"Our next step is to determine whether we can re-inject or engraft the expanded sperm-producing stem cells into patients after they are cancer free," said Ryeom.